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  • 1
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    Flexible space structure model reduction by modal cost analysis (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: It is noted that reduced models and reduced controllers for flexible space structures are obtained by retaining those modes which make the greatest contribution to quadratic control objectives. Attention is given to the relative importance of damping, frequency and mode shapes in the mode truncation decisions for the following control objectives: attitude control, vibration suppression and figure control. It is also shown that using Modal Cost Analysis (MCA) on the closed loop modes of the optimally controlled system allows the construction of reduced control policies which feedback only those closed loop coordinates which are most critical to the quadratic control performance criterion. In this manner, the modes which need to be controlled are deduced from truncations of the optimal controller.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Dynamics and control of large flexible spacecraft; Jun 21, 1979 - Jun 23, 1979; Blacksburg, VA
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Controllability and observability for flexible spacecraft (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Current interest in extended sensing and actuation for the control of flexible spacecraft has led to the use of modern multivariable control theory and the associated concepts of controllability and observability. This paper shows how to evaluate these properties on a mode-by-mode basis for flexible spacecraft control analysis. Relatively simple criteria are derived which indicate the degree of controllability (observability) of each mode in simple literal terms. These criteria provide physical insight and practical guidance on the type, number, and positioning of sensors and actuators. The results are interpreted for force and torque actuators, and for attitude and deformation measurements. To illustrate these ideas, sample controllability and observability 'surfaces' are presented for the Purdue generic flexible spacecraft model.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Dynamics and control of large flexible spacecraft; Jun 21, 1979 - Jun 23, 1979; Blacksburg, VA
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Dynamics of incremental motion devices associated with planetary exploration spacecraft (1975)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Incremental motion devices provide accurate and rapid movement of spacecraft science platforms, antennas and related mechanisms. The paper considers the computerized simulation of a stepper motor/gear train/ science platform system that will be launched on the Mariner Jupiter Saturn 1977. It was determined that a smaller stepper motor could be used as the prime mover for the science platform, and it was concluded that the existing digital controller was unable to achieve the required pointing accuracy, and a new controller design was necessary.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Annual Symposium on Incremental Motion Control Systems and Devices; Apr 01, 1975 - Apr 03, 1975; Urbana, IL
    Format: text
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    NASA TECHNICAL REPORTS
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